1. Field of the Invention
The present invention relates mainly to a structure of an upper rotating body having a cab, which is used in a construction machine such as a hydraulic excavator.
2. Description of the Prior Art
FIG. 7 is an entire side view of a back hoe described as an embodiment in Japanese Patent Laid Open No. 302739/96. In the same figure, numeral 5 denotes a rotating base of the back hoe, numeral 7 denotes a cabin, numeral 20 denotes a bonnet formed at a rear portion of the cabin 7, numeral 20a denotes an engine hood of the bonnet 20, and numeral 20c denotes a fixed hood. FIG. 8 is a plan view of the rotating base 5 shown in FIG. 7. In FIG. 8, numeral 24 denotes a rear panel of the cabin 7, numeral 18 denotes an engine, numeral 16 denotes a fuel tank, and numeral 17 denotes an oil tank (a hydraulic oil tank). FIG. 9 is a left side view of the cabin 7 shown in FIGS. 7 and 8. In FIG. 9, numeral 23 denotes a left side panel of the cabin 7, numeral 27 denotes an operator seat formed within the cabin 7, and numeral 36 denotes a seal member.
In the conventional back how shown in FIGS. 7 to 9, the rear portion of the cabin 7 is covered with the fixed hood 20c (shown in FIGS. 7 and 8) which serves as a guard. In the space surrounded by the fixed hood 20c, the rear wall of the cabin 7, the engine hood 20a and a counterweight, there are mounted such devices as a power source and hydraulic devices though not shown. In order to ensure a space behind the cabin 7, a lower portion of the rear wall of the cabin is inclined so as to protrude toward the inside of a cab.
According to this conventional back hoe, a space is formed in a rear lower portion of the cabin 7 to arrange devices therein, which space is connected to the interior of the fixed hood 20c. In a small-sized hydraulic excavator in which devices are compelled to be arranged in a narrow space, the said space serves as an effective space for the arrangement of devices therein.
In the above conventional back how, the fixed hood 20c is disposed between the cabin 7 and the engine hood 20a to protect the devices from contact with rain drops and obstacles and attain a pleasing appearance.
Such a conventional structure requires the provision of an additional guard (the fixed hood 20c in the conventional back hoe shown in FIGS. 7 and 8), thus resulting in an increase in the number of components used and hence deterioration of productivity. Moreover, the appearance of the machine body is deteriorated because of an increase in the number of joint portions, and a problem is encountered also in point of durability of the guard mounting portion.
For example, these problems may be solved if the engine hood 20a is extended up to the rear wall of the cabin 7. In this case, however, the engine hood 20a becomes larger in size and it extends into rear lower portions of side walls of the cabin 7. Such a shape is presumed to make opening and closing of the engine hood difficult. Besides, intra-vehicle width rotating type construction machine wherein an upper rotating body is completely rotatable within the width of a lower travel body, such as the conventional back hoe, and rear end intra-vehicle width rotating type construction machines wherein only the rear end of an upper rotating body is rotatable within the width of a lower travel body, are popular in recent years in which construction works carried out in narrow places such as those in cites occupy a considerable proportion of all the construction works. However, from the nature of the machines, it is required to increase the weight of a counterweight attached to the rear end of upper rotating body in order to ensure stability. To meet this requirement, such a counterweight as extends up to near the height of the engine hood is sometimes mounted. In a construction machine having such a counterweight, it is necessary to use a guard for covering between the front edge of the counterweight and the cabin. If the front edge of the counterweight is extended up to near the rear edge of the cabin, the function as the guard may be fulfilled. In this case, however, a sideways portion of the rotating center, where the counterweight is less influential, becomes heavier and therefore, the weight of the machine body increases to an unnecessary extend, thus giving rise to a problem also from the point of transportability of the machine body.